High ambient temperatures negatively affect power output and the efficiency of gas turbine systems. More specifically, warm air drawn in by a gas turbine system has a lower air density when compared to the air density of cooler air. As a result, the warm air provides the gas turbine with a lowered air mass flow, which results in a loss in power output of the gas turbine system. In gas turbine systems, inlet fogging systems reduce the temperature of inlet air drawn into the compressor of the gas turbine system. The process of fogging reduces the temperature of the inlet air, which creates a higher air mass flow of the inlet air, and allows the compressor to compress the inlet air using a reduced work load per unit inlet air massflow. This reduced work load of the compressor provides the gas turbine system with higher power output.
Conventionally, inlet fogging systems require several hundred or thousands of fogging nozzles connected to high pressure pumps. The high pressure pumps provide demineralized water to the nozzles at pressures substantially higher than atmospheric pressure (e.g., 20 MPa). This is to ensure the conventional nozzles will produce water droplets small enough in diameter such that the water droplets in the “fogged” inlet air will evaporate before reaching the compressor or the droplets are so fine that they do not damage components in the passages. In the conventional inlet fogging systems the nozzles typically consist of a variety of high-pressure spray nozzles to produce water spray having a droplet size of about 20 micrometers. The high pressure forces the water bursting out of the conventional nozzle at a high exit velocity. As a result, the conventional nozzles are replaced annually under typical operation conditions due to excessive water abrasion to the nozzles. Additionally, conventional inlet fogging systems utilize a very low flow rate of the water through the conventional nozzles to also aid in producing a spray having a desired droplet size of about 20 micrometers.
However, if the supply pressure drops in providing the water to the conventional nozzles, the droplet size provided to the inlet air may vary and may have lognormal distribution with much larger droplets. As the water droplet size increases, it becomes more difficult for the water droplets to completely evaporate before reaching the compressor. If the water droplets do not completely evaporate, portions of the inlet duct, the compressor blades and compressor housing may become saturated. Overtime, the saturation of the inlet duct, compressor blades and compressor housing can lead to impingement damage erosion or other forms of material breakdown in these components. Once the material properties of the compressor have been compromised, the efficiency is reduced and replacement of damaged parts or the entire compressor is required. Although utilizing an inlet fogging system can improve the hot day turbine output degradation performance, conventional inlet fogging systems often require replacing materially compromised components of the gas turbine system as a result of less-than optimum operation of the conventional inlet fogging system.